The present invention relates to a golf club and more particularly to a wood-type golf club having a specific relationship between the gravity point of its relatively large-sized club head and the torsional rigidity of the club shaft by which the head rebounds fully at impact.
In recent years, metal wood-type golf clubs having a head volume over 250 cc are widely used.
AS the increasing in the head volume leads the club head to a large moment of inertia, even if the golfer makes a miss shot off the sweet spot, the movement or reaction of the club head at impact becomes less, and the deterioration in the directional stability of hitting and loss of carry may be reduced. Therefore, large-sized golf club heads are preferred by many golfers, and the head volume is increasing and now reaches to 400 cc or more.
However, when the size of the club head is increased, the distance of the gravity point from the center line of the club shaft is basically increased. During the downswing, the club head is subjected to a force to rotate the club head around the club shaft center line. This force increases substantially in proportion to the increase in the gravity point distance. Therefore, in the case of a club head whose gravity point distance is long, as shown in FIG. 8, which shows the head motion during the downswing from a moment proximate to impact to impact, the club face is likely not to fully rebound to a state of being square at impact. As a result, there is a tendency to slice a shot or to miss a shot towards a different direction B (a right direction B in the case of the right-handed golfer) than the direction A of the target trajectory. Such a tendency is especially high in the case of average golfers.
As a countermeasure for preventing such a miss shot, it has been known to provide a club face having a relatively large hook angle (or face angle). This method is premised on the fact that the club face does not rebound completely to a normal state where the club face becomes square. Thus, this is not a fundamental solution. Further, if the hook angle becomes large, it becomes difficult to address or feel odd.